1. Field of Art
This invention relates to a sprocket arrangement for feeding rounds onto the face of a gun bolt.
2. Prior Art
The classic modern revolving battery gun is shown by R. J. Gatling in U.S. Pat. No. 125,563 issued Apr. 9, 1872. A stationary housing encloses and supports a rotor assembly which has a plurality of gun barrels and a like plurality of gun bolts. Each gun bolt is reciprocated longitudinally by a stationary elliptical cam track in the housing. The rounds are fed in forward of each gun bolt when the bolt is in rear dwell, and the bolt picks up its respective round as it comes forward. In the feeding systems shown in U.S. Pat. Nos. 3,333,506 issued to R. W. Henshaw et al. on Aug. 1, 1967 and 3,380,342, issued to R. E. Chiabrandy on Apr. 30, 1968, there is shown the conventional system of a sprocket turning within spiral shaped guides for feeding rounds onto the face of a gun bolt while the bolt is in rear dwell. This is the system utilized in the M61 Vulcan gun and used in the declutching feeder or the transfer unit therefor. A similar system is utilized in the GAU-8/A gun. A different system, utilizing an expanding feeder sprocket, was utilized in a different, prototype version of the GAU-8/A gun, as shown in FIG. 56 of Technical Report AFATL-TR-73-130, Vol. 1, June 1973. Another different system, utilizing a non-constant rotational velocity sprocket is shown in U.S. Pat. No. 3,915,058 issued to Folsom et al. on Oct. 28, 1975. In all of these systems the bolt remains in rear dwell until the round is centered on the face of the gun bolt.
The rear dwell time, i.e., the increment of angular rotation of the rotor required for the gun bolt to remain in rear dwell, is one of the determinants of the increment of angular rotation of the rotor available for the acceleration, constant velocity and deceleration of the gun bolt. The greater the increment available for such acceleration, constant velocity and deceleration, for a given maximum cam slope, the smaller the diameter of the cam which may be used. The smaller the cam diameter, the smaller the diameter of the gun, and also the lower the power required to drive the gun.